Late Roman ranks

[D B Campbell]

The name lochagoi, sounds Greek......is it?

Yes.

I was reading the book by D'Amato on centurions and he mentioned the name lochagoi.

I have not seen that book, but I expect D'Amato has his reasons!

Polybius calls a centurion a ταξίαρχος (literally, "commander of a taxis", a file of soldiers roughly 100 strong, according to the technical manuals), and Josephus calls a centurion a ἑκατοντάρχης (literally, "commander of one hundred"). λοχαγός, by contrast, is a fairly general word for a commander (literally, "commander of a lochos"), since the lochos could vary wildly in size. The technical manuals use it for a very small unit of men, which makes me wonder at the use of lochagos to mean centurion.